Field
The present disclosure relates to an apparatus and system for simulating maintenance of a reactor core protection system including at least two or more channels, the simulation apparatus including a simulation signal generation unit for generating a state signal including a normal state or an abnormal state, a communication unit connected to each of the channels of the reactor core protection system to transmit the state signal to the channel, and a control unit for receiving a result signal output from the channel in response to the input state signal and confirming whether the reactor core protection system normally determines a reactor core state by analyzing the result signal.
Background of the Related Art
Nuclear power generation is generation of electricity by operating a turbine generator using steam generated by boiling water using energy generated by a fission chain reaction. Since huge energy is generated as the energy needed for generating free particles by completely separating nucleons from atomic nuclei configured of protons and neutrons is emitted, the nuclear power generation is the most desirable power source capable of obtaining a lot of energy using an extremely small amount of fuel, and most countries in the world producing electricity use the nuclear power generation.
However, in the case of the nuclear power generation, a great danger is accompanied in using the nuclear energy, and thus a large number of safety devices are necessarily required together with control of highly trained experts. Particularly, in the case of the nuclear power generation, a state of a system for protecting the core of a reactor is most carefully inspected, and even in normal times when an accident of nuclear power generation does not occur, whether or not a nuclear power generator, sensing devices installed in the nuclear power generator and computing devices for analyzing the sensing devices properly operate should be confirmed.
Accordingly, a reactor core protection system corresponds to a system for monitoring a degree of nuclear reaction of the reactor core and controlling to shut down the reactor to protect the reactor core when an excessive state occurs.
Referring to FIG. 1a, a conventional reactor 110 simultaneously senses various state signals through four different channels including first to fourth channels 121 to 124. At this point, the state signals carry various state data of the reactor of the nuclear power generator, including a temperature, a pressure, a rotation speed, a flow rate and the like. Since safety should be considered above all in the case of nuclear power generation, the conventional reactor transmits one state data to four different computing devices (channels) so that each computing device may determine abnormality of the state data.
At this point, it is designed to maintain electrical and physical independence among the channels in order to objectively grasp an abnormal state of the reactor, and if two or more channels simultaneously determine an abnormal situation after receiving the state data and generate a trip signal, countermeasures such as temporarily shutting down the reactor or the like will be taken. This is to cope with occurrence of a failure in the channels themselves, and although the first channel among the first to fourth channels is out of order and determined as an abnormal situation, if the second to fourth channels are determined as a normal situation, the reactor will not be shut down, and unnecessary waste of resources may be prevented.
Meanwhile, a control rod of a bar shape covered with a material easily absorbing thermal neutrons exists in the reactor core. In the case of the control rod, reactivity of nuclear fuel is adjusted by inserting and withdrawing the control rod into and out of the reactor core. If the control rod is inserted, reactivity of the reactor is lowered, and if the control rod is removed, reactivity of the reactor is increased. Accordingly, if an abnormal situation occurs in the reactor, the control rod is inserted for emergency shutdown of the reactor, and the reactor can be shut down by fully inserting the control rod.
Although a conventional reactor core protection system also confirms the position of the control rod 112 at all times, in the case of a control rod position signal, dozens of different signals should be sensed unlike the state data described above, such as a temperature, a pressure and the like, since one reactor includes a plurality of control rods, and thus control rod position signals are divided to be transmitted over two channels due to the limit of the channels in receiving signals. Accordingly, dozens of the control rod position signals are divided, and first and second channels 121 and 122 receive values of the divided signals, and third and fourth channels 123 and 124 receive values of the divided signals. Then, the first channel and the second channel exchange their values to make a final determination by integrating all the control rod position signals.
For example, if there are fifty control rod position signals in total, the first channel may receive thirty control rod position signals, and the second channel may receive twenty control rod position signals. Subsequently, the first channel transmits its thirty control rod position signals to the second channel, and the second channel transmits its twenty control rod position signals to the first channel. In conclusion, the first channel and the second channel respectively receive all the fifty control rod position signals and determine a normal state and an abnormal state. If an abnormal state is determined, a trip signal is generated, and a manager or an expert solves the corresponding abnormal state.
Meanwhile, in the case of a reactor, safety should be guaranteed by sensing a variety of state data in real-time as described above, and since huge damage may occur with only a single accident, it should be regularly confirmed whether the channels for sensing an abnormal state of a reactor properly work when an abnormal state occurs in the reactor. Accordingly, a simulation apparatus for simulating a signal generated in the reactor and inputting the signal in a channel and determining whether the channel properly responds is indispensable.
Referring to FIG. 1b, a sensing sequence of equipment for sensing a control rod position signal may be confirmed. Conventional response time test equipment (RTTE) 130 is connected to the first to fourth channels 121 to 124 and inputs a simulation state signal into the channels using the simulation apparatus. At this point, the simulation apparatus is connected to each of the channels and generates first to fourth control rod position signals 131 to 134.
The simulation apparatus inputs the first control rod position signal into the first channel 121 and the second control rod position signal into the second channel 122. The second channel 122 transfers the input second control rod position signal to the first channel 121, and the first channel 121 integrates the first control rod position signal and the second control rod position signal and finally determines an abnormal state. If it is determined as an abnormal state, the first channel 121 generates a trip signal 135 and transmits the trip signal to the simulation apparatus 130.
However, in the case of the conventional reactor core protection system, if a response time is measured for a situation of generating a trip signal by the first channel based on the control rod position signal transferred to the first channel 121 by way of the second channel 122, since the conventional simulation apparatus has a disadvantage of connecting only one simulation apparatus to one channel, the simulation apparatus itself cannot measure the response time, and the response time test equipment 130 should be used. Furthermore, there is a problem in that one simulation apparatus may simulate a state signal input into one channel.
Therefore, a simulation apparatus for inspecting the conventional reactor core protection system should use additional equipment to test a response time while connecting four channels and should connect hundreds of different resistors to a terminal block. In addition, the simulation should be conducted by connecting the simulation apparatus to a channel which will be tested mainly, using the response time test equipment for a control rod position signal which needs a signal change among the other channels and connecting resistors for the remaining control rod position signals.
Accordingly, the simulation apparatus for inspecting the conventional reactor core protection system may not conduct all the needed tests within an inspection time since a lot of time is consumed to set a test environment, and since existing external wires should be separated when the resistors are connected and wired again after the test is finished, this may induce a human error or a failure of the terminal block. Furthermore, there are restrictions in simulating various dynamic signals.
Furthermore, the simulation apparatus for inspecting the conventional reactor core protection system may change a simulation signal to a type such as a step signal, a ramp signal or the like only once, and a communication signal may delay a corresponding signal, and there is a problem in that a pump speed signal that should be simulated using a pulse signal cannot be dynamically simulated together with other signals and can be changed only individually.